Paper tabs are used in the office, home, school, and the like for a variety of applications. Often they are included as section dividers in a booklet or notebook to provide convenient indexing of the various sections. Although small, stick-on tabs can be provided with, e.g., a pressure sensitive adhesive allowing them to be merely attached to the edge of a page in the booklet, more often the tabs are provided as integrally formed with a sheet of paper (often of heavier stock) the same size as the booklet pages, except of course that the tab itself extends beyond one edge of the pages. Typically the tabs will be reinforced in some fashion to withstand the often heavy wear they must endure. Usually the reinforcement is accomplished by adhering a layer of Mylar.RTM. or similar film to one or both sides of the tab.
To serve their potential function fully, preferably tabs are printed with specific information relating to the section or page(s) that they are identifying. For example, tabs segmenting a book into ten sequential sections may be printed with the numbers 1-10. Other information is also common, such as months, days, chapter titles, and the like. When custom information, tailored to a particular application, is desired, the information is sometimes manually written on the tabs. Alternately, special tabs may be used that utilize a clear plastic sleeve containing a paper insert on which is typed or printed the information to be displayed. These methods typically are not very professional looking, are not well suited to mass production of many copies, and the paper inserts often fall out of their sleeves.
To address these deficiencies, many companies have custom tabs manufactured to meet their specific needs. Unless a significant number of copies of such tabs are needed, however, this option can be quite costly.
Xerographic techniques for the production of relatively high quality booklets have recently become quite advanced. For example, Xerox Corporation currently sells a line of duplicating systems (e.g., the "Xerox 50 Series") that not only yield high quality xerographic reproductions but also collate, staple/bind, and insert front and back covers. These systems also can insert non-reinforced tabbed sheets at desired locations within the booklets, with the desired information reproduced on the body of the sheet as well as on the tab, allowing, in effect, custom printing of the tabs.
These tabbed sheets are usually of heavier stock but are otherwise not reinforced. Although copiers of this type are capable of handling heavier stock paper precut with tabs, the tabs themselves cannot be reinforced with a Mylar.RTM.-type film, since the film typically adds about 50-100% (or more) to the thickness of one edge of the sheet. A stack of such sheets will build up thicker on the reinforced edge, making it quite uneven. Such a stack cannot be handled by the sheet feeders of these copiers.
Moreover, reinforcing films utilized to date are not particularly receptive to xerographic toner. Even if the toner initially adheres to the film, usually it is relatively easy to scrape off and/or it flakes off if the tab is flexed, bent, or creased. Thus, such films are not suited for production of high-quality custom reinforced tabs.
Although unreinforced tabs can and typically are made out of heavier stock paper, under substantial use they tend to fold or crease along the edge of the booklet pages. They also tend to delaminate, as the reader typically engages the very edge of the tab with a finger, tending to peel the upper layers of the unprotected edge away from the lower layers.